Polymerization of bis(2-bromo-4,6-dichloro- phenoxo)bis(pyridine) copper (11) complex in DMF by electroinitiation D. Klsak0rek, S. Sen, L. Aras and L. TLirker Department of Chemistry, Middle East Technical University, Ankara, Turkey and L. Toppare Department of Science, Middle East Technical University, Ankara, Turkey (Received 25 January 1990; accepted 21 May 1990) Polymerization of bis(2-bromo-4,6-dichlorophenoxo)bis(pyridine) copper (II) complex was achieved in dimethylformamide by electrooxidation. A cyclic voltammogram (CV) of the complex was obtained in dimethylformamide in advance. Constant potential yielded polymers in anode compartment only under nitrogen atmosphere and air. In the final polymer product, incorporation of neither the ligand nor the copper was observed and the post-polymerization proceeded in the absence of current. The structural analyses of the polymers were done by 13C n.m.r., 1H n.m.r., FTi.r. spectroscopy, differential scanning calorimetry (d.s.c.) and dipole moment measurements. The molecular weight of the polymer was determined by cryoscopic method. The poly(dihalophenylene oxides) obtained at different potentials were found to be similar in structure and both 1,2 and 1,4 catenations took place at roughly equal rates. (Keywords: electroinitiated polymerizations; bis(2-bromo-4,6-dichlorophenoxo)bis(pyridine) copper (II) complex; poly(dihalophenylene oxide)) INTRODUCTION minations. Lower molecular weight polymers than previously available 7 are usually obtained in electro- In a series of papers, polymerization of trihalophenols initiation polymerization of trihalophenoxo copper (II) under a variety of conditions has been reported ~ 16. comp lexes11,12,14,15. Originally, decompositions of the silver salts of sym- In this study, electroinitiated polymerization of bis(2- metrically substituted halogenated phenols I and later, those having the same halogen in the two ortho positions bromo-2,6-dichlorophenoxo)bis(pyridine) copper (II) com- plex was carried out. There are no records in literature and a different one in the para positions were studied 2. about the electroinitiated polymerization of this complex. Novel synthesis was achieved from the decomposition of The control of the polymerization potential also leads to a bis(trihalophenoxo) copper (II)complexes using various selective initiation generally, in comparison to other ligands thermally ~9' 13 and electrochemically~°-I 2,14,15. methods. The exact anodic and cathodic peak potentials Many variations of bromine and chlorine atoms in 2,4 of the complex were measured simultaneously by cyclic and 6 positions of the phenol were tried. Polymerization voltammetry (CV) in acetonitrile containing 0.1 M of 4-bromo, 2,6-dichlorophenoxide yielded a polymer tetrabutylammonium fluoroborate (TBAFB) prior to with a high proportion of !,4 catenation units indicating electroinitiated polymerization. a high selectivity for displacement of bromine rather than chlorine 5'16. Polymerization of 4-chloro, 2,6-dibromo- Br phenoxide yielded a polymer with a high proportion of S~c ~ /CH, ~ /Nk_~ 1,2 catenate unit in N,N,N',N'-tetramethylethylene- cl o ~N\ CL 0 \ /, \ diamine 15 (A) and with pyridine ligand an equal amount Xcu/CH2 Cu' of 1,2 addition and 1,4 addition units ~°'~4 by electro- .... Initiation. The intent was to put bromine in the ortho / position and having chlorine atoms in the para and other cl o -- N-- CH~ Cl 0 \CH 3 ortho positions to promote 1,2-coupling in thermal cL cl decomposition of bis(2-bromo-4,6-dichlorophenoxo)bis (a) /b) (pyridine) copper (II) complex (C) 7's. This was not the case, however, from elemental analysis, ~H n.m.r., ~3C n.m.r, spectra 7's'16 and radius of gyration 17 studies. It cl~OY -ao /-~-(" was reported that somewhere between one half and two "~c~ X thirds of the available bromine was displaced ~6 and the cu branches were monomeric 7. e/~____<or / One of the major problems encountered was the c,~o achievement of sufficiently low molecular weight poly- c~ mer samples for spectral analysis in structural deter- /c) 0032-3861/'91/'071323~)6 't2" 1991 Butterworth HeinemannLtd. POLYMER, 1991, Volume 32, Number 7 1323